1. Technical Field of the Invention
Implementations consistent with the principles of the invention generally relate to the field of disk drive technology, more specifically to methods of manufacturing piezo-capable base plate assemblies.
2. Background
In conventional hard disk drives, data are stored on magnetizable surfaces of a plurality of rotating disks that are mounted in a coaxial stack on a housing of the drive. As shown and described in U.S. Pat. No. 7,190,555, which is incorporated herein by reference in its entirety, transducer heads that write data to and read data from the disk surfaces may be supported by an actuator that is mounted on the same housing and can be actuated to position the transducer heads in alignment with concentric data tracks defined on the disks. Each transducer head may be attached to one end of a head suspension that is connected to an actuator arm that extends from the actuator body. Each suspension may include a flexible base plate. The suspension may act as a spring that forces the head against the disk surface with an accurate load force or “gram load”. An air bearing caused by the rotating disks may lift the heads slightly off of the disks so that the heads fly at a specific height across the disk surfaces. The air bearing force may be counteracted by the suspension gram load.
The head suspension may be attached to an actuator arm using a conventional swage mount that forms a part of the head suspension. The combined swage mount, base plate, and actuator arm make up the head suspension, and the suspension has the hub of the swage mount extending beyond the base plate and concentric with the clearance hole.
FIG. 1 illustrates a disc drive assembly 100 including an actuator arm 110, a base plate 120 and a swage mount 130. A fully assembled disk drive may have an actuator arm assembly and a stack of spaced-apart disks rotatable about a separate axis. The arm assembly may include a plurality of actuator arms 110, which extend into the spaces between the disks. One such actuator arm 110 is shown in FIG. 1. Attached to the actuator arm near the tip 140 may be a base plate 120. The actuator arm 110 when assembled in a stack with a number of identical actuator arms may rotate about the actuator arm axis 150.
The base plate 120 may include a base section 160 having a base plate boss hole 170. The base plate 120 may include a resilient section 180 located between the base section 160 and a protrusion section 190 of the base plate 120. The resilient section 180 may be formed to create an angular offset between the base section 160 and protrusion section 190. The degree of bending of the suspension may determine the downward preload force of a slider toward a disk surface. The geometry of the base plate in resilient section 180 and/or the size of an aperture 200 in the resilient section 180 may establish the resilience of the base plate 120.
Piezo-driven actuation may be used to deform/deflect the base plate to induce lateral motion of the protrusion section 190 of base plate 120. As shown in FIG. 2, a pair of piezoelectric microactuators 210 may be attached to opposite sides of aperture 200 in the resilient section 180 of base plate 120. Differential electrical charges may be applied to each of piezoelectric microactuators 210 to pivot protrusion section 190 of base plate 120 relative to base section 160 of base plate 120.
Various designs of piezo-capable base plates have been attempted in the art. Many designs are difficult to handle after fabrication due to nesting and interlocking of plates. For example, in the exemplary piezo-capable base plate of FIG. 2, the aperture 200 may permit interpenetration of multiple base plates after fabrication and before installation of piezoelectric microactuators 210. Handling of piezo-capable base plates may be difficult and may cause problems with bonding piezoelectric elements. Many of the designs in the art lack out-of-plane and lateral stiffness, which can undesirably lower the resonant frequency of various suspension modes. Current manufacturing attempts have failed to provide a sufficiently compliant base-plate flange in the longitudinal piezo actuation direction.
Thus, there is a need in the art for a cost effective means of manufacturing base plates, while addressing the above issues or other limitations in the art.
There is a need in the art for base plates that prevent nesting and interlocking of multiple parts during fabrication and transfer from initial fabrication to a later point in the assembly process, such as the bonding of piezoelectric elements to the base plate or ultimate incorporation into a disk drive assembly.